Various types of printed material are applied to the surface of molded objects, particularly plastic objects. This material typically can be names of products, their manufacturer, various designs, instructions, etc. All of this material can be generally grouped under the title "graphics". One of the most common methods for adding such graphical information to objects is to apply pre-printed "label" material with glue. While this may be expedient for the mass production of some objects, the labels are easily damaged upon abrasion thereof.
For objects of lower production rates, and where the graphics are desired to be more durable, the graphical information is actually formed in the outer surface of the object. This is conventionally accomplished by applying a "transfer" of the graphics upon the surface of the mold prior to the formation of the object. The graphics transfer is usually prepared by silk screen techniques upon a release paper such that the image, with the transfer paper attached, can be placed against the mold surface followed by the removal of the transfer paper (after laboriously pressing to assure adherence of the transfer to the mold surface) prior to the molding. As a result, graphical information of a few mils (e,g, 5-10) of thickness is achieved in the surface of the molded object. This is similar to the method described in the below-cited U.S. Pat. No. 5,152,861. While graphics achieved with this method are significantly more durable, there is considerable cost in the silk screening process and each molded item requires a new transfer. Also, there is lost time in causing the transfer to adhere.
Various plastic molding techniques involving the introduction of color and/or elements such as metal flakes are described in U.S. Pat. No.: 5,232,644 issued to D. Hammond, et al, on Aug. 3, 1993; U.S. Pat. No. 5,262,108 issued to J. Minke, et al, on Nov. 16, 1993; U.S. Pat. No. 5,316,715 issued to J. Gray on May 31, 1994; and U.S. Pat. No. 5,324,472 issued to W. Page, et al, on Jun. 28, 1994.
Other U.S. Patents that may be generally related to the present invention are: U.S. Pat. No. 4,126,727 issued to S. Kaminski on Nov. 21, 1978; U.S. Pat. No. 4,307,058 issued to E. Morello, et al, on Dec. 22, 1981; U.S. Pat. No. 4,443,392 issued to J. Becker, et al, on Apr. 17, 1984; U.S. Pat. No. 4,645,556 issued to R. Waugh, et al, on Feb. 24, 1987; U.S. Pat. No. 5,152,861 issued to G. Hann on Oct. 6, 1992 U.S. Pat. No. 5,211,593 issued to S. Schneider, et al, on May 18, 1993; and U.S. Pat. No. 5,264,172 issued to G. Rosica, et al, on Nov. 23, 1993.
A rotational molding process is utilized by Dagger, Inc. in Roane County, Tennessee, to manufacture kayaks. A quantity of a selected polyethylene powder is introduced into a mold having an internal surface corresponding to a desired kayak surface shape. The mold is heated, while being rotated, such that the powder is transformed into a molten plastic state to form the kayak hull. Upon a complete transformation of the powder and distribution throughout the mold, the mold is cooled and removed from the kayak hull. Thereafter, any finishing details are performed to complete the fabrication of the kayak. Many of the kayaks have various decorative graphical material to meet customers requests and for sales appeal. They also have the company logo. The logo, as well as a number of the requested graphics, must have high definition: that is, the edges of the design must be very sharply defined.
In order to achieve high definition, both of the above-described methods of achieving graphics upon the exterior of the kayak have been employed. Obviously, a kayak is subjected to considerable abrasion so that labels applied to the surface have a very short life.
The method of applying a transfer graphic to the mold has achieved a more durable graphic presentation. However, the thickness is limited and damage does occur. The cost is very high for a one-of-the-kind graphic. Also, a new transfer is used for each kayak and, if multiple graphical designs are to be applied to each hull, there is a significant cost involved because each transfer must be prepared by silk screening (or a similar process) and then carefully transferred to the mold.
Accordingly, it is an object of the present invention to provide a method for the preparation of high definition graphics within the surface of molded objects.
It is another object of the present invention to provide a method for the preparation of high definition graphics in the surface of objects molded from plastic powders.
A further object of the present invention is to provide a method for achieving high definition graphical design in the surface of kayaks molded from plastic powder in rotational molding equipment.
Another object of the present invention is to provide a method for achieving high definition graphical design in the surface of kayaks molded from plastic powder in rotational molding equipment wherein re-usable patterns are used to significantly reduce the cost of such graphical design.
These and other objects of the present invention will become apparent upon a consideration of the drawings that follow, together with a complete description thereof.